Emulsions with improved stability

Abstract

Disclosed are methods of lowering application viscosities of or of reducing or eliminating monomer content in electrical impregnating materials comprising or consisting of an emulsion of an unsaturated polyester or a mixture of unsaturated polyesters, water, at least one radical polymerisation initiator or radical polymerisation initiator/promoter mixture, at least one surfactant having an HLB-value of greater than 15, optionally at least one reactive diluent, and optionally further additives, a process for preparing zero or low VOC electrical impregnation materials, a method of impregnating electrical or electromechanical devices and a method of increasing the stability of aqueous emulsions of unsaturated polyesters.

What is claimed is: 
     
         1 . A method of lowering the application viscosity of an electrical impregnating material to between 2,000 mPas and 100 mPas, or a method of reducing or eliminating monomer content in an electrical impregnating material and at the same time reducing application viscosity to between 2,000 mPas and 100 mPas, wherein the method comprises employing as electrical impregnation material a zero or low VOC emulsion comprising or consisting of
 a1) an unsaturated polyester or a mixture of unsaturated polyesters,   a2) water,   b) at least one radical polymerisation initiator or a mixture of radical polymerisation initiator and promoter,   c) at least one surfactant having an HLB-value of greater than 15,   d) optionally, at least one reactive diluent, and   e) optionally, further additives.   
     
     
         2 . The method of  claim 1 , wherein a1) comprises one or more resins selected from dicyclopentadienyl (DCPD) containing resins, imide functionality containing resins, and mixtures thereof. 
     
     
         3 . The method of  claim 1 , wherein the initiator is selected from dicumylperoxide, t-butylbezoperoxide, and mixtures thereof. 
     
     
         4 . The method of  claim 1 , wherein herein the reactive diluent is selected from vinyl monomers, (meth)acrylate monomers, oligomers of these, and mixtures thereof. 
     
     
         5 . The method of  claim 1 , wherein the reactive diluent is selected from DAP, VT, 1,4-butanediol dimethacrylate, propoxylated glyceryl triacrylate, and mixtures thereof. 
     
     
         6 . A method of impregnating or coating an electrical or electromechanical device, wherein the method comprises adding a zero or low VOC emulsion to the electromechanical device and curing the applied emulsion, the zero or low VOC emulsion comprising or consisting of
 a1) an unsaturated polyester or a mixture of unsaturated polyesters,   a2) water,   b) at least one radical polymerisation initiator or a mixture of radical polymerisation initiator and promoter,   c) at least one surfactant having an HLB-value of greater than 15,   d) optionally, at least one reactive diluent, and   e) optionally, further additives.   
     
     
         7 . The method of  claim 6 , wherein the emulsion is added to the electromechanical device by at least one of dipping, spraying, casting, trickling. 
     
     
         8 . The method of  claim 6 , wherein the electromechanical device is a magnet wire. 
     
     
         9 . The method of  claim 6 , wherein a1) comprises one or more resins selected from dicyclopentadienyl (DCPD) containing resins, imide functionality containing resins, and mixtures thereof. 
     
     
         10 . The method of  claim 6 , wherein the initiator is selected from dicumylperoxide, t-butylbezoperoxide, and mixtures thereof. 
     
     
         11 . The method of  claim 6 , wherein herein the reactive diluent is selected from vinyl monomers, (meth)acrylate monomers, oligomers of these, and mixtures thereof. 
     
     
         12 . The method of  claim 6 , wherein the reactive diluent is selected from DAP, VT, 1,4-butanediol dimethacrylate, propoxylated glyceryl triacrylate, and mixtures thereof. 
     
     
         13 . A low viscosity, zero or low VOC electrical impregnating material, wherein the material has an application viscosity of from 2000 mPas to 100 mPas and comprises or consists of an emulsion comprising or consisting of
 a1) an unsaturated polyester or a mixture of unsaturated polyesters,   a2) water,   b) at least one radical polymerisation initiator or a mixture of radical polymerisation initiator and promoter,   c) at least one surfactant having an HLB-value of greater than 15,   d) optionally, at least one reactive diluent, and   e) optionally, further additives.   
     
     
         14 . The electrical insulation material of  claim 13 , wherein the material has an application viscosity of from 200 mPas to 800 mPas. 
     
     
         15 . The electrical insulation material of  claim 13 , wherein a1) comprises one or more resins selected from dicyclopentadienyl (DCPD) containing resins, imide functionality containing resins, and mixtures thereof. 
     
     
         16 . The electrical insulation material of  claim 13 , wherein the initiator is selected from dicumylperoxide, t-butylbezoperoxide, and mixtures thereof. 
     
     
         17 . The electrical insulation material of  claim 13 , wherein the reactive diluent is selected from vinyl monomers, (meth)acrylate monomers, oligomers of these, and mixtures thereof. 
     
     
         18 . The electrical insulation material of  claim 13 , wherein the reactive diluent is selected from DAP, VT, 1,4-butanediol dimethacrylate, propoxylated glyceryl triacrylate, and mixtures thereof. 
     
     
         19 . A process for preparing a zero or low VOC electrical impregnating material by preparing an emulsion of unsaturated polyesters comprising or consisting of
 a1) an unsaturated polyester or a mixture of unsaturated polyesters,   a2) water,   b) at least one initiator for radical polymerisation or initiator for radical polymerisation/promotor mixture,   c) at least one surfactant having an HLB-value of greater than 15,   d) optionally at least one reactive diluent, and   e) optionally further additives,   wherein the process comprises mixing a1), a2), b), d) and e) to form a homogenous unsaturated polyester containing mixture and   separately mixing a2) and c) until homogenous to form a water/surfactant mixture and   thereafter adding the unsaturated polyester containing mixture to the water/surfactant mixture under shear mixing,   and employing a resultant emulsion for or as electrical impregnating varnish.   
     
     
         20 . A method of increasing the stability of aqueous emulsions of unsaturated polyesters comprising or consisting of
 a1) an unsaturated polyester or a mixture of unsaturated polyesters,   a2) water,   b) at least one initiator for radical polymerisation or initiator for radical polymerisation/promotor mixture,   c) at least one surfactant,   d) optionally at least one reactive diluent, and   e) optionally further additives,   wherein the method comprises employing as surfactant at least one surfactant having an HLB-value of greater than 15.